Being current, Jet should have all the parts. If I remember looking at Jets, their trunnions were pretty light weight. It is a current product isn't it? Looks like it is pretty expensive considering what a Harvey costs for a lot more tool. Replacement parts are always expensive.
Look at the parts manuals for other C-frame Jets, laguna, Grizley, Baleigh, Oliver, Delta, Harbor Freight, older Craftsman, Ridgid. Powermaric, PorterCable etc. There are only a couple of actual OEMs so parts were mostly grab bag.
As a last resort, there are several plans for a DIY band saw made of plywood. One could adapt/copy their table and trunnions. Probably stronger than Jet. If you don't need tilt, a lot easier. You could weld something up out of angle iron pretty easy and make a table large enough to be useful.